Device for purifying water

ABSTRACT

The invention relates to a device ( 2 ) for purifying water ( 6, 9 ) contaminated with organic substances, that is drained or collected from filters, especially fuel filters ( 4 ) or elements of a fuel system. Said device is characterised in that hydroxyl radicals are formed from the water ( 6, 9 ) by means of a separating device ( 8 ), said hydroxyl radicals oxidising the impurities, especially organic substances, as much as possible, and converting them into compounds such as CO 2 .

The invention relates to a device for purifying water which is drained or collected from filters, especially fuel filters or elements of the fuel system, and which is contaminated with organic matter.

In order to ensure the operational reliability of drive units, such as in particular internal combustion engines, which are to be supplied with liquid fuels, it is conventional to provide fuel supply systems with water-separating fuel filters. The separation of water which is contained or entrained in particular in diesel fuel is called for to protect the sensitive injection system from damage. The water which has been separated in these systems is loaded with various types of organic matter, for example, with suspended droplets of oil from the diesel fuel flowing through the fuel filter. Therefore, for reasons of environmental protection, the release of water which has been separated from the fuel filter systems into the environment without further treatment is not an option.

With respect to these problems, the object of the invention is to make available a device for purifying water which has been separated from fuel supply systems, which device, although it can be easily and economically operated, enables effective removal of the organic loads so that the purified water can be released into the environment quite safely.

According to the invention, this object is achieved by a device having the features specified in claim 1 in its entirety.

Accordingly, the important particularity of the invention resides in the fact that the device has a separating means by which hydroxyl radicals can be separated from the water to be purified, so that said hydroxyl radicals oxidize the organic matter as much as possible into inorganic compounds such as CO₂. Since hydroxyl radicals are chemically highly reactive, they are able to develop such a high oxidation potential that organic loads such as, for example, oil-water emulsions or suspended diesel droplets in the water which has been separated from diesel fuel filters are oxidized almost completely into CO₂.

In especially advantageous exemplary embodiments, the separating means has an electrolysis apparatus and/or hydroxyl radical-forming media, for example, catalysts such as titanium dioxide.

When the hydroxyl radicals are produced by splitting water by means of electrolysis, the configuration can be made especially advantageously such that the electrolysis apparatus has at least one diamond electrode which is anodically active during electrolysis. A special water decomposition can be achieved by means of a diamond electrode which is electrically conductive due to doping with the element boron. While water is typically split into hydrogen and oxygen during electrolysis, the diamond electrode provides a working range in which highly reactive hydroxyl radicals are formed instead of oxygen and hydrogen.

In advantageous exemplary embodiments, the electrolysis apparatus can have two diamond electrodes which, energized with polarity reversal, act in alternation as anode and cathode, it being possible to operate the device with alternating current.

If alternatively a diamond electrode is acting as anode for the electrolysis, a high-grade steel electrode is preferably used as the cathode. Said steel electrode is subjected to cathodic protection during electrolysis according to the method of electrochemical protection, as is used for corrosion protection, for example, in tanks or ships.

Preferably, the arrangement is made such that the device has a treatment chamber downstream of the pertinent fuel filter for the water which is to be purified, which chamber has a controllable outlet or conveyor device or overflow for the purified water as well as the separating means in order to make contact between the water in the treatment chamber and the hydroxyl radicals which have been formed.

Instead of the arrangement of electrolyzing electrodes, the separation means can have a body which is located in the treatment chamber and which contains or is coated with titanium dioxide and forms the hydroxyl radicals which make contact with the water.

In especially advantageous exemplary embodiments, it is furthermore provided that the separating means, preferably in addition to the part of the means which produces hydroxyl radicals and which is located in the treatment chamber, has a filter medium which is provided with titanium dioxide for the formation of hydroxyl radicals in the associated fuel filter.

To promote the formation of hydroxyl radicals by titanium dioxide, the separating means can have a means for supply of radiant energy. For this purpose, there can be an artificial or natural light source, preferably with wavelengths from 180 to 300 nm.

Depending on where the formation of the hydroxyl radicals by titanium dioxide takes place, a radiation source of this type can be provided for irradiation of the treatment chamber and/or of the interior of the fuel filter.

The invention is detailed below using exemplary embodiments shown in the drawings.

FIG. 1 shows a functional diagram of one exemplary embodiment of the device according to the invention and

FIG. 2 shows a representation of a second exemplary embodiment of the device corresponding to FIG. 1.

The invention is explained below using examples in which the purification device 2 is integrated into the fuel supply system such that water 6 which has been removed from a water-separating fuel filter 4 is drained directly into a tank 8 of the device 2, which tank forms a treatment chamber. It goes without saying that the purification device 2 can also form a unit which is separate from a fuel supply system and in which captured water is purified.

In the examples described here, the fuel filter 4 is located in the route of the fuel line 10, and fuel, for example, diesel fuel, flows through it before it is delivered to a system to be supplied (not shown), for example, the injection pump of a diesel engine. The water 6 which has been separated in the filter 4 is drained directly into the tank 8 of the device 2. The tank 8 forms a treatment chamber for drained water 9 with controllable drain 12 and controllable outlet 14 by means of which a feed amount of water 9 to be purified for a specified treatment interval is kept collected using level sensor means which are conventional in the art and is released after completed purification.

In the two exemplary embodiments of FIG. 1 and FIG. 2, the water 6, 9 originating from the fuel filtering is purified by the oxidation of organic loads such that these loads are brought into contact with highly reactive hydroxyl radicals in the tank 8, which is used as a treatment chamber. In the two exemplary embodiments, the hydroxyl radicals are split off from the water molecules in the tank 8, using a separating means. In the exemplary embodiment of FIG. 1, for this purpose, water decomposition takes place by electrolysis, which is carried out by means of two diamond electrodes 16 and 18. While water typically is split into hydrogen and oxygen during electrolysis, a diamond electrode 16, 18 yields a working range in which highly aggressive hydroxyl radicals are formed instead of oxygen.

The diamond electrodes 16, 18 can be formed such that a crystalline diamond layer only few microns thick from hydrogen gas and a hydrocarbon gas such as methane is applied to a conductive substrate at very high temperatures between 2000° C. and 3000° C., rendering the diamond layer electrically conductive by doping with the element boron.

If, as in the exemplary embodiment of FIG. 1, the two electrodes 16 and 18 are diamond electrodes, electrolysis can take place by applying an AC voltage whereby, corresponding to polarity reversal, one electrode 16 or 18 at a time acts as anode and the other electrode 16 or 18 as cathode. Alternatively, the arrangement can be made such that only one of the electrodes—in the example shown in FIG. 1, the electrode 16—is a diamond electrode and is connected to the positive terminal 20 of a DC voltage source. In this case, the electrode 18, which is connected to the negative terminal 22 and which is acting as cathode, is a high-grade steel electrode. In operation, a cathodic protection thus arises for the electrode 18 acting as cathode, corresponding to conventional methods of electrochemical protection for corrosion protection of tanks or ships.

In any event, the high oxidation potential of the hydroxyl radicals which have been formed ensures that the organic substances found in the water as load are oxidized into harmless inorganic compounds, especially into CO₂ which escapes from the tank 8. The purified water can then be safely released into the environment.

FIG. 2 shows one example in which a chemical separating means is used instead of a separating means made as an electrolysis apparatus, specifically such that a titanium dioxide-containing body 30 located in the tank 8 is brought into contact with the water 9 to be purified. Making contact with titanium dioxide results in the splitting of hydroxyl radicals from the pertinent water 9. As has been found, this chemical mechanism can be enhanced by a supply of radiant energy. The supply of radiant energy can take place by an artificial or natural light source 24 which irradiates the contents of the tank within the tank 8. A wavelength range from 180 to 300 nm has proven especially effective. The light source 24 can be sunlight, lights such as LEDs, or the like.

In the two exemplary embodiments of FIG. 1 and FIG. 2, it can also be provided that the fuel filter 4 is provided with a filter medium 26 which has a coating with titanium dioxide so that a separating means for splitting off hydroxyl radicals from the water 6 is already formed in the fuel filter 4. The resulting purification can replace the water purification in the tank 8 or in addition thereto can be provided as a preliminary purification. As in the separating means within the tank 8, there can also be an arrangement for the supply of radiant energy as a reaction enhancement means for the separating means formed in the fuel filter 4, in this example another light source 28.

The invention enables effective purification with a device which is simple to operate and which does not require any consumable materials, but simply requires a supply of electrical energy for electrolysis or optionally for radiation sources in the form of light sources 24, 28. 

1. A device (2) for purifying water (6, 9) which is drained or collected from filters, especially fuel filters (4) or elements of a fuel system, and which is contaminated with organic matter, characterized in that a separating means (8) forms hydroxyl radicals from the water (6, 9), said hydroxyl radicals oxidizing the impurities, especially organic matter, as much as possible and converting them into compounds such as CO2.
 2. The device according to claim 1, characterized in that the separating means has an electrolysis apparatus (16, 18, 20, 22) and/or hydroxyl radical-forming media (30), such as titanium dioxide.
 3. The device according to claim 2, characterized in that the electrolysis apparatus has at least one diamond electrode (16) which acts as anode during electrolysis.
 4. The device according to claim 2, characterized in that the electrolysis apparatus has two diamond electrodes (16 and 18) which, energized with polarity reversal, act in alternation as anode and cathode.
 5. The device according to claim 1, characterized in that it has a treatment chamber (8) downstream of the pertinent fuel filter (4) for the water (6, 9) which is to be purified, which chamber has a controllable outlet (12) or conveyor device or overflow (14) for the purified water and the separating means (16, 18; 30) in order to make contact between the water (9) located in the treatment chamber (8) and the hydroxyl radicals which have been formed.
 6. The device according to claim 5, characterized in that the separating means has a body (30) which is located in the treatment chamber (8) and which contains titanium dioxide or is coated with it and which forms the hydroxyl radicals which make contact with the water (9).
 7. The device according to claim 5, characterized in that the separating means, preferably in addition to the part (16, 18; 30) of the means which produces the hydroxyl radicals and which is located in the treatment chamber (8), has a filter medium (26) which is provided with titanium dioxide for formation of hydroxyl radicals in the associated fuel filter (4).
 8. The device according to claim 1, characterized in that to promote the formation of hydroxyl radicals by titanium dioxide, the separating means has a means (24, 28) for supply of radiant energy.
 9. The device according to claim 8, characterized in that there is a radiation source (24, 28) for irradiation of the treatment chamber (8) and/or of the interior of the fuel filter (4). 